Insulator.



W. T. GODDARD. INSULATOR. APPLICATION man mu: 1. ms.

Patented Sept. 11, 1917.

WITNESSES:

f I Zw uromns WALTER T. GODDARD, 0F HAMILTON, ONTARIO, CANADA.

INSULATOR.

Application filed June 7, 1916.

[0 all whom it may concern.

Be it known that I, WALTER T. GODDARD, a citizen of the United States, residing at Hamilton, Province of Ontario, Dominion of tianada, have invented certain new and useful Improvements in Insulators; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specification. and to the reference-numerals marked thereon.

My invention relates to insulators with special reference to those employed for supportim high frequency current conductors, being designed more particularly for application to radio work, and has for its purpose to afford a novel and efiicient means for effecting a serviceable joint or connection between a noneonducting substance like porcelain and a conducting material such as metal. In a more specific aspect, the invention has to do with attaching a metal or conducting cap upon an insulating section or member so that a tight and lasting joint is secured, and without seriously affecting or in any manner interfering with the current transmission. To these and other ends the invention consists in certain improvements and combinations of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings:

Figure 1 is a side elevation of an insulator showing an application of my invention;

Fig. 2 is a longitudinal central sectional view;

Fig. 3 is a transverse section on line 33 of Fig. 2, and

Fig. 4 is a detail view of a modified pin.

Similar reference numerals in the several figures indicate the same parts.

It is to be understood that the particular type of insulator herein illustrated and described is intended merely as exemplary to show the manner in which the purpose of the improvement is carried out, and the invention is likewise applicable to various types of insulators, wherever it may be expedient to attach a cap or other portion of conducting material, such metal, to a nonconducting member of porcelain or similar material. This has been accomplished heretofore in several ways, the most com- Specification of Letters Patent.

Patented Sept. 11, 1917. serial No. 102,287.

mon of which is to employ cement between the metal and the porcelain, and this has presented several objections, chief among which is that the cement joint is not applicable where high frequency currents are employed, as the latter has the effect of quickly destroying the cement, and thus rendering the joint useless. A further disadvantage of a cement connection is found in temperature effects, which by reason of the different coefiicients of expansion of metal and cement are likely to bring undue strain on the porcelain, which is thereby damaged or broken. Where high frequency currents are present, it is essential that the exterior surface of the conducting material be perfectly smooth, and free from projecting points or surface obstructions in order to prevent brush discharges, and my invention is designed with this in view as one of its purposes, and to provide a mechanical union, without the use of cement between conducting and non-conducting materials, affording a strong and durable connection that will successfully withstand any strains ordinarily imposed upon it. In the illustrative embodiment of the present application, 1 designates the insulating member which is provided in its periphery with a plurality of locking recesses or apertures 2, its end being surrounded by a cap 3 of conducting material such as metal, and to which the conductor is connected in the usual manner in accordance with this class of devices. The cap 3 is spaced slightly from the insulating member, as shown in Fig. 2, and provided with a plurality of openings 4 extending therethrough, and threaded to receive the securing devices, which are preferably in the form of threaded pins 5. The pins 5 are in threaded engagement with the openings 4, which are preferably slightly larger than the pins to permit equal distribution of the load, and when finally positioned, the outer ends of the pins are arranged within the openings, and the inner ends engaged with the locking recesses 2, as clearly shown in- Figs. 2 and 3. The securing devices or pins 5 are removable from the openings 4, and extend inwardly beyond the inner surfaces of the cap, forming a rigid joint, which serves to hold the cap in tight relation with the insulating member. while at the same time permitting relative expansion and contraction under changes in temperature.

The recesses 2 retain the cap rigidly in place without materially weakening the porcelain, as a continuous groove would, and the strength of the porcelain is proportionate its extreme outer diameter, owing to the portions lyingbetween the recesses. It may be desired to engage the porcelain by a soft metal, and in such case, I may employ a steel securing pin 6, having an inner en of soft copper or lead for contact with the porcelain, to afford a more intimate connection.

For radio work, it is desirable that the exterior or outer surface of the cap be entirely smooth, and with this end in contemplation, I fill the openings 4, beyond the outer ends of the securing pins, with a suitable substance, such as cement, lead, or the like, to afford a surface continuous or flush with the exterior of the cap, and this results in efl'ectively obviating brush discharges that would otherwise take place, more particularly with high frequency currents. The invention is, however, applicable to any type of insulator where it is desired to eliminate cement joints.

I claim as my invention:

1. The combination with an insulating five cents each, by

member having a locking recess in its pe riphery, of a conducting cap having a threaded opening, a securing device threaded within said opening with its inner end extending beyond the cap and engaging the locking recess, and a filling material in the opening adjacent to the outer end of the securing pin and forming a surface continnous with the exterior of the cap.

2. The combination with an insulating member having a plurality of locking recesses in its periphery, of a conducting cap arranged in spaced relation to the insulating member and having a plurality of threaded openings corresponding to said locking recesses, and securing devices arranged in the threaded openings of the conducting cap and extending into the aforesaid lockin recesses within the periphery of the insu ating member, whereby the cap is held upon the insulating member in spaced relation without a cement connection.

WALTER T. GODDARD.

Witnesses:

EUGENE M. ERIGKSON, CHARLES H. CLEVELAND.

addressing the Commissioner of Patents,

Washington, D. 0. 

